Flow meters are used in fluid systems to measure the rate of fluid flow through fluid conduits. Flow meters may be used for measuring fluid flow in fluid pipeline systems, within wellbores of well or drilling systems, and in other industrial applications. A common type of flow meter used in industrial applications are venturi flow meters which create a restriction within the fluid flow path and measure the resulting pressure differential formed in the fluid flowing through the meter. Due to their resistance to erosion, venturi flow meters may be used in downhole or wellbore applications with abrasive fluids or slurries, or in applications including multiphase fluid flow. Additionally, venturi flow meters may be used in high fluid flow rate applications.
In some applications, venturi flow meters may include a reduced diameter section or “throat” that forms a restriction in the fluid passageway of the flow meter. In some applications, fluid pressure is measured within the throat of the flow meter and at a position upstream of the throat, where the fluid pressure within the throat is decreased versus the upstream section due to an increase in the rate of fluid flow through the throat according to the Bernoulli principle. By comparing the difference in measured fluid pressure between the throat and the upstream section with the ratio of inner diameters of the throat and upstream section (known as the “beta ratio” of the flow meter), the rate of fluid flow through the flow meter may be inferred through well-known equations.
In some applications, the venturi flow meter is designed with a predetermined beta ratio configured to provide accurate fluid flow rate measurements within a predetermined fluid flow rate range. In other words, a venturi flow meter's beta ratio may only provide accurate flow rate measurement within a corresponding flow rate range, where deviation from the particular flow rate range by the flowing fluid may result in inaccurate or imprecise measurement of the fluid flow rate by the meter, limiting the flexibility of the meter in measuring the rate of fluid flow therethrough.